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    <title>ShellCheck: SC2081 – `[ .. ]` can't match globs. Use `[[ .. ]]` or grep.</title>
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    <h1>SC2081 – ShellCheck Wiki</h1>
    <a href="https://github.com/koalaman/shellcheck/wiki/SC2081">See this page on GitHub</a>
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    <h2 id="---cant-match-globs-use----or-grep"><code>[ .. ]</code> can't
match globs. Use <code>[[ .. ]]</code> or grep.</h2>
<h3 id="problematic-code">Problematic code:</h3>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC2081.html#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> <span class="bu">[</span> <span class="va">$var</span> <span class="ot">==</span> <span class="pp">*</span>[^0-9]<span class="pp">*</span> <span class="bu">]</span></span>
<span id="cb1-2"><a href="SC2081.html#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="cf">then</span></span>
<span id="cb1-3"><a href="SC2081.html#cb1-3" aria-hidden="true" tabindex="-1"></a>  <span class="bu">echo</span> <span class="st">&quot;</span><span class="va">$var</span><span class="st"> is not numeric&quot;</span></span>
<span id="cb1-4"><a href="SC2081.html#cb1-4" aria-hidden="true" tabindex="-1"></a><span class="cf">fi</span> </span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC2081.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> <span class="kw">[[</span> <span class="va">$var</span> <span class="ot">==</span> <span class="pp">*</span>[^0-9]<span class="pp">*</span> <span class="kw">]]</span></span>
<span id="cb2-2"><a href="SC2081.html#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="cf">then</span></span>
<span id="cb2-3"><a href="SC2081.html#cb2-3" aria-hidden="true" tabindex="-1"></a>  <span class="bu">echo</span> <span class="st">&quot;</span><span class="va">$var</span><span class="st"> is not numeric&quot;</span></span>
<span id="cb2-4"><a href="SC2081.html#cb2-4" aria-hidden="true" tabindex="-1"></a><span class="cf">fi</span> </span></code></pre></div>
<h3 id="rationale">Rationale:</h3>
<p><code>[ .. ]</code> aka <code>test</code> can not match against
globs.</p>
<p>In bash/ksh, you can instead use <code>[[ .. ]]</code> which supports
this behavior.</p>
<p>In sh, you can rewrite to use <code>grep</code>.</p>
<div class="sourceCode" id="cb3"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb3-1"><a href="SC2081.html#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> <span class="bu">echo</span> <span class="va">$var</span> <span class="kw">|</span> <span class="fu">grep</span> <span class="at">-q</span> <span class="st">&#39;^[0-9]*$&#39;</span><span class="kw">;</span> <span class="cf">then</span></span>
<span id="cb3-2"><a href="SC2081.html#cb3-2" aria-hidden="true" tabindex="-1"></a>  <span class="bu">echo</span> <span class="st">&quot;</span><span class="va">$var</span><span class="st"> is numeric&quot;</span></span>
<span id="cb3-3"><a href="SC2081.html#cb3-3" aria-hidden="true" tabindex="-1"></a><span class="cf">fi</span></span></code></pre></div>
<h3 id="exceptions">Exceptions:</h3>
<p>None. If you are not trying to match a glob, quote the argument (e.g.
<code>[ $var == '*' ]</code> to match literal asterisk.</p>
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